Door release mechanism

ABSTRACT

A door hoist includes a bracket, drive sprocket, ring gear, hub assembly, set of planetary gears, and governor shaft. The drive sprocket has a drive sprocket axis. The ring gear is fastened to the drive sprocket. The ring gear has a ring gear axis that is in alignment with the drive sprocket axis. The hub assembly includes a connector to receive a door drive shaft and secure the door drive shaft in a fixed rotational alignment with the hub assembly. The set of planetary gears is rotationally mounted to the hub assembly. The set of planetary gears is configured to mate with the ring gear. The governor shaft includes a sun gear, brake assembly, and link. The sun gear is configured to mate with the set of planetary gears. The brake assembly has an engaged position and a disengaged position. The sun gear is rotationally fixed relative to the bracket in response to the brake assembly being in the engaged position. In response to the brake assembly being in the disengaged position, rotation of the sun gear is unfixed relative to the bracket. The link secures the brake assembly in the engaged position. The link is configured to melt in response to an ambient temperature exceeding a predetermined temperature.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a divisional of U.S. application for patent Ser. No.12/987,684 filed Jan. 10, 2011 and entitled “DOOR RELEASE MECHANISM,”which is a divisional of U.S. application for patent Ser. No. 11/976,363filed on Oct. 24, 2007, also entitled “DOOR RELEASE MECHANISM” andissued as U.S. Pat. No. 7,878,230, the disclosures of which are herebyincorporated by reference in their entirety.

FIELD OF THE INVENTION

The present invention generally relates to a door hoist. Moreparticularly, the present invention pertains to a device and system forautomatically releasing a door in response to an event.

BACKGROUND OF THE INVENTION

Conventionally, door hoist systems are utilized to operate a variety ofdoors. Particular examples of doors operated via a door hoist includerolling type, sectional, and the like. These types of doors aretypically utilized for controlling access to garages, ware houses, etc.In the event of a fire, it is generally beneficial to close these doorsto limit the amount of oxygen supplied to the fire and slow the spreadof fire from one side of the door to the other.

Conventional electronic fire door systems are generally electronicallyor computer operated. Such systems are costly to design, install, andmaintain. In addition, conventional electronic fire door systems aregenerally significantly larger than a standard door hoist. As such,retrofitting electronic fire door systems into an existing building mayrequire structural alteration of the building. As a result, theinstallation and maintenance of electronic fire door systems may be costprohibitive in some instances.

Accordingly, it is desirable to provide a method and apparatus capableof overcoming the disadvantages described herein at least to someextent.

SUMMARY OF THE INVENTION

The foregoing disadvantages are overcome, at least to a great extent, bythe present invention, wherein in one respect, a device and system isprovided that in some embodiments automatically releases a door inresponse to an event.

An embodiment of the present invention pertains to a door hoist tooperate a door. The door hoist includes a bracket, drive sprocket, ringgear, hub assembly, set of planetary gears, and governor shaft. Thedrive sprocket has a drive sprocket axis and is fastened to a ring gear.The ring gear has a ring gear axis that is in alignment with the drivesprocket axis. The hub assembly includes a connector to receive a doordrive shaft and secure the door drive shaft in a fixed rotationalalignment with the hub assembly. The set of planetary gears isrotationally mounted to the hub assembly. The set of planetary gears isconfigured to mate with the ring gear. The governor shaft includes a sungear, brake assembly, and link. The sun gear is configured to mate withthe set of planetary gears. The brake assembly has an engaged positionand a disengaged position. The sun gear is rotationally fixed relativeto the bracket in response to the brake assembly being in the engagedposition. In response to the brake assembly being in the disengagedposition, rotation of the sun gear is unfixed relative to the bracket.The link secures the brake assembly in the engaged position.

Another embodiment of the present invention relates to a fire door hoistsystem to operate a door and automatically close the door in response toa fire. The fire door hoist system includes a door hoist and doorrelease assembly. The door hoist operates the door. The door hoistincludes a bracket, drive sprocket, ring gear, hub assembly, set ofplanetary gears, and sun gear. The drive sprocket has a drive sprocketaxis and is fastened to a ring gear. The ring gear has a ring gear axisthat is in alignment with the drive sprocket axis. The hub assemblyincludes a connector to receive a door drive shaft and secure the doordrive shaft in a fixed rotational alignment with the hub assembly. Theset of planetary gears is rotationally mounted to the hub assembly. Theset of planetary gears is configured to mate with the ring gear. The sungear is configured to mate with the set of planetary gears. The doorrelease assembly automatically releases the door in response to thefire. The door release assembly includes a governor shaft, brakeassembly, and link. The governor shaft is secured to the sun gear. Thebrake assembly has an engaged position and a disengaged position. Thegovernor shaft is rotationally fixed relative to the bracket in responseto the brake assembly being in the engaged position. In response to thebrake assembly being in the disengaged position, the rotation of thegovernor shaft is unfixed relative to the bracket. The link secures thebrake assembly in the engaged position.

Yet another embodiment of the present invention pertains to a door hoistto operate a door. The door hoist includes a bracket, drive sprocket,set of planetary gears, hub assembly, ring gear, and governor shaft. Thedrive sprocket has a drive sprocket axis and is rotationally fastened tothe set of planetary gears. The set of planetary gears has an axis thatis in alignment with the drive sprocket axis. The hub assembly includesa connector to receive a door drive shaft and secure the door driveshaft in a fixed rotational alignment with the hub assembly. The ringgear is fastened to the hub assembly. The ring gear is configured tomate with the set of planetary gears. The governor shaft includes a sungear, brake assembly, and link. The sun gear is configured to mate withthe set of planetary gears. The brake assembly has an engaged positionand a disengaged position. The sun gear is rotationally fixed relativeto the bracket in response to the brake assembly being in the engagedposition. In response to the brake assembly being in the disengagedposition, rotation of the sun gear is unfixed relative to the bracket.The link secures the brake assembly in the engaged position.

There has thus been outlined, rather broadly, certain embodiments of theinvention in order that the detailed description thereof herein may bebetter understood, and in order that the present contribution to the artmay be better appreciated. There are, of course, additional embodimentsof the invention that will be described below and which will form thesubject matter of the claims appended hereto.

In this respect, before explaining at least one embodiment of theinvention in detail, it is to be understood that the invention is notlimited in its application to the details of construction and to thearrangements of the components set forth in the following description orillustrated in the drawings. The invention is capable of embodiments inaddition to those described and of being practiced and carried out invarious ways. Also, it is to be understood that the phraseology andterminology employed herein, as well as the abstract, are for thepurpose of description and should not be regarded as limiting.

As such, those skilled in the art will appreciate that the conceptionupon which this disclosure is based may readily be utilized as a basisfor the designing of other structures, methods and systems for carryingout the several purposes of the present invention. It is important,therefore, that the claims be regarded as including such equivalentconstructions insofar as they do not depart from the spirit and scope ofthe present invention.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of a door system according to an embodimentof the invention.

FIG. 2 is an exploded view of the hoist according to an embodiment ofthe invention.

FIG. 3 is a simplified view of a release assembly in an engaged positionaccording to an embodiment of the invention.

FIG. 4 is a simplified view of the release assembly in a disengagedposition according to the embodiment of FIG. 3.

FIG. 5 is a simplified view of a release assembly in an engaged positionaccording to another embodiment of the invention.

FIG. 6 is a simplified view of the release assembly in a disengagedposition according to the embodiment of FIG. 5.

FIG. 7 is a detailed view of a horizontally oriented actuator engaging adrive sprocket according to another embodiment of the invention.

FIG. 8 is a detailed view of a vertically oriented actuator engaging adrive sprocket according to yet another embodiment of the invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

In various embodiments of the invention a simplified device and systemare provided to automatically release a door in response to an event. Ina particular example, the device is configured to close a door in theevent of a fire. For example, when attached to a door that is biased toclose, a release assembly connecting a hoist assembly to the doorassembly may be configured to release the door assembly from the hoistassembly in response to a fire or smoke. Released from the hoistassembly, the door may be allowed to close. In another example, therelease assembly may be configured to release the door assembly from thehoist assembly in response to a security incident. In yet anotherexample, the release assembly connects the hoist assembly to a doorassembly that is biased to open. In this example, the release may becontrolled to release the door assembly from the hoist assembly tofacilitate egress through the door. In comparison to electronicallycontrolled or computer controlled door closing systems, this simplifieddevice is easier, less expensive, and less time consuming tomanufacture. For the consumer, this simplified device is easier and lessexpensive to install and maintain in comparison to electronicallycontrolled door closing systems.

An embodiment of the invention will now be described with reference tothe drawing figures, in which like reference numerals refer to likeparts throughout. As shown in FIG. 1, a door system 10 includes a door12 and a hoist 14. The door 12 may include any suitable door or othersuch covering structure operable to cover an opening. In general, thedoor 12 may include rollup, swing, sliding, etc. type doors. In aparticular example, the door 12 is a conventional rollup type doorconfigured to slide within a track 16 and roll up into a cover 18. Suchrollup type doors are well known to include a cylinder or shaft withinthe cover 18 to operate the door 12. That is, the door 12 is drawn intothe cover 18 by rotating the shaft and rolling the door about the shaftor a cylinder connected to the shaft. The door 12 is controlled orallowed to close by rotating the shaft in the opposite direction and/orallowing gravity to draw the door 12 downwards. In this regard, the door12 is biased in the closed position. A door that is otherwise suitablefor use with various embodiments of the invention but is not biased inthe closed position may be modified to be biased in the closed position.For example, a spring or weight or other such door closing device may beadded to the door.

The hoist 14 according to various embodiments may be operated via anysuitable mechanism. In several particular examples shown in insets A, B,and C, the hoist 14 may include a chain drive 20 or motor 22 and themotor 22 may be mounted vertically or horizontally. A particular exampleof the chain drive 20 is shown in FIG. 2. Particular examples ofvertically and horizontally mounted motors 22 are shown respectivelyshown in FIGS. 5 and 6.

FIG. 2 is an exploded view of the hoist 14 according to an embodiment ofthe invention. As shown in FIG. 2, the hoist 14 includes a chain hoistwheel assembly 24, unidirectional brake assembly 26, drive assembly 28,door release assembly 30, and bracket 32. The chain hoist wheel assembly24 is optional and in this or other embodiments, any suitable actuatormay be substituted. For example, the motor 22 may replace the chainhoist assembly 28. If present, the chain hoist assembly 24 includes achain 34, chain hoist wheel 36, chain drive sprocket 38, chain guards40, and chain hoist shaft 42. To operate the door 12, the chain 34 maybe pulled by a user to urge the chain hoist wheel 36 to rotate. Thechain drive sprocket 38 is integral to or fastened to the chain hoistwheel 36. As a result, rotation of the chain hoist wheel 36 induces acorresponding rotation of the chain drive sprocket 38. In turn,operation of the chain hoist wheel assembly 24 urges the drive assembly28 to raise or lower the door 12. As is generally known, inducing arotation of the drive assembly 28 in a first direction causes the door12 to raise and inducing an opposite rotation causes the door 12 tolower.

The unidirectional brake assembly 26 is optionally included to accompanyactuating assemblies that lack sufficient self-braking characteristics.If present, the unidirectional brake assembly 26 includes a brakepressure plate 44, brake pad 46, ratcheted pressure plate 48, spring 50,pawl 52, and mounting plate 54. The brake pressure plate 44, brake pad46, ratcheted pressure plate 48, and spring 50 are mounted to the chainhoist shaft 42. The brake pressure plate 44 is pinned or otherwise fixedto rotate with the chain hoist shaft 42. The pawl 52 is mounted to themounting plate 54 or the bracket 32. The ratcheted pressure plate 48includes one or more detents or teeth to engage the pawl 52. In thismanner, the ratcheted pressure plate 48 is configured to rotate in afirst direction and the ratcheted pressure plate 48 is stopped fromrotating in a reverse rotational direction by the interaction of thepawl 52 and teeth.

The chain hoist wheel assembly 24 shown in FIG. 2 may provide so littlerotational resistance that, barring additional intervention, the door 12may tend to fall closed. To reduce this tendency, the unidirectionalbrake assembly 26 is configured to provide resistance to rotation whichresults in a downward movement of the door 12. To ease the operation ofraising the door 12, the unidirectional brake assembly 26 rotatessubstantially freely in the direction of rotation that raises the door12.

In other instances, the chain hoist wheel assembly 24, motor 22, orother such actuator may provide sufficient rotational resistance toretain the door 12 in an open position. For example, a worm gear (shownin FIG. 6) may be employed to urge the drive assembly 28 to rotate. Thedirection of torque transmission (input shaft vs. output shaft) is notreversible in conventional worm gear trains. In this or other suchinstances, the unidirectional brake assembly 26 may be omitted.

The drive assembly 28 according to various embodiments provides asimplified gear train in comparison to conventional door hoists. Thissimplified gear train reduces the material and labor costs, reduces thesize of the hoist 14, and may increase reliability. It is a furtheradvantage of the drive assembly 28 that the door release assembly 30 isfully integrated into this simplified gear train and shares componentstherewith. This further simplifies the door system, which results in afurther reduction of material and labor costs.

As shown in FIG. 2, the drive assembly 28 includes a drive sprocket 56,annulus or ring gear 58, sun gear 60, set of planetary gears 62, hubassembly 64, and connector 66. The drive sprocket 56 is arranged orconfigured to mate with the chain drive sprocket 38 or similar such gearof the motor 22 or other such actuator. In an embodiment, the ring gear58 is integral to or fixed to the drive sprocket 56. In a particularexample, the ring gear 58 is welded to the drive sprocket 56 with acentral or rotational axis of the ring gear 58 coinciding with a centralaxis of the drive sprocket 56. The sun gear 60 is disposed to coincidewith the central axis of the ring gear 58. The set of planetary gears 62is disposed between the ring gear 58 and the sun gear 60 and configuredto mate with both. While the number of individual planetary gears in theset of planetary gears 62 may vary, such gear trains typically includeat least a pair, and more typically four, individual planetary gears tobalance and distribute loads throughout the gear train. The hub assembly64 may serve as a planet carrier for the set of planet gears 62. In thiscapacity, the ring gear 58 functions as the input shaft, the rotation ofwhich causes the set of planet gears 62 to rotate about a fixed sun gear60 and the hub assembly 64 is the output shaft to operate the door 12.In this regard, the connector 66 is fixed to the hub assembly 64. Theconnector 66 is configured to receive and rotationally secure a doorshaft 68. The door shaft 68 operates the door 12 and may be secured tothe connector 66 in any suitable manner. In a particular example, thedoor shaft 68 includes a channel for a spline 67, the connector 66includes a channel for the spline 67, and the door shaft 68 andconnector 66 are locked in rotational alignment by the insertion of thespline 67 into the channel. In other examples, the door shaft 68 andconnector 66 may include mating “D” or square configurations, and/or maybe welded, press fit, or otherwise fastened together.

In another embodiment, the ring gear 58 is integral to or fixed to thehub assembly 64 and the set of planetary gears 62 are rotationallymounted to the sprocket 56. That is, the sprocket 56 may serve as aplanet carrier for the set of planet gears 62. In addition, otherarrangements of the gear train are within the scope of the invention.

The door release assembly 30 includes a governor shaft 70, governor 72,plate 74, drop arm 76, and link 78. The governor shaft 70 is secured tothe sun gear 60. In various examples, the sun gear 60 may be press fit,pinned, splined, or otherwise fixed to the governor shaft 70. Thegovernor 72 includes any suitable governing device such as, for example,a viscous governor, mechanical, brake-type governor, and the like. Thegovernor 72 includes a hub that is fixed to the governor shaft 70. Theplate 74 is secured to the governor shaft 70. In various examples, theplate 74 may be press fit, pinned, splined, or otherwise fixed to thegovernor shaft 70. The plate 74 includes at least one point or toothconfigured to engage a corresponding point, indent, or tooth on the droparm 76. The drop arm 76 includes two ends. A first end is pivotallyfixed with respect to the plate 74. The second end is secured via thelink 78. In this secured position, the drop arm 76 and the plate 74 areconfigured to preclude rotation of the governor shaft 70. In response toremoval of the link 78 or loss of structural integrity of the link 78,the drop arm 76 is allowed to swing or pivot about the first end anddisengage from the plate 74. In this disengaged position, the plate 74and therefore the governor shaft 70 are free to rotate.

According to an embodiment of the invention, at a predeterminedtemperature, the link 78 is configured to soften, melt, or otherwiselose sufficient structural integrity to retain the drop arm 76. Thepredetermined temperature may be set according to a variety of factors.These factors may include, for example, expected normal ambienttemperature, manufacture's recommendation, empirical data, and the like.To facilitate manual operation and/or testing of the door system 10, thelink 78 may be attached to the drop arm 76 via a line 80 and the line 80may be attached to a handle or switch 82. As shown in FIGS. 4 and 5, theswitch 82 may be moved from a first to a second position to control thedrop arm 76. In another example, the link 78 may pass through a hole inthe bracket 32 to secure the drop arm 76 and a ring or handle may remainoutside of a housing. In this manner, the ring provides a grippingsurface to remove the link 78 and is readily available to test the doorsystem 10.

According to another embodiment, the link 78 may include an electronicrelease device such as, for example, an electromagnetically coupledlink, solenoid release device, or the like. In this embodiment, the link78 may release the drop arm 76 in response to any suitable event suchas, for example, a smoke alarm activation, security event, manualactivation of a switch, and the like.

FIG. 3 is a simplified view of the drop arm 76 and plate 74 in theengaged position according to FIG. 2. As shown in FIG. 3, the drop arm76 is secured to the link 78 via the line 80. In addition, the switch 82is shown in a first configuration. In this first configuration, the line80 is controlled to retain the drop arm 76 in the engaged position. Whensecured in the engaged position, the drop arm 76 and plate 74 locktogether to prevent the plate 74 from turning. In turn, the governorshaft 70 is prevented from turning by the engaged plate 74. That is, thegovernor shaft 70 is rotationally fixed relative to the bracket 32 inresponse to the door release assembly 30 being in the engaged position.

FIG. 4 is a simplified view of the drop arm 76 and plate 74 in thedisengaged position according to FIG. 2. As shown in FIG. 4, in responseto disposing the switch 82 in a second position or compromising thestructural integrity of the link 78, the drop arm 76 is configured todrop from the engaged position. As the drop arm 76 pivots away from theplate 74, the plate 74 is free to rotate. In this manner, the doorrelease assembly may be controlled to release the door 12. Dependingupon the bias of the door 12, releasing the release assembly may raiseor lower the door 12. In a particular example, the door 12 may be biasedto close and the door system 10 is configured to automatically close thedoor 12 in response to the ambient temperature exceeding thepredetermined temperature. It is an advantage of the door system 10 thatthis automatic closure may proceed in a complete absence of electricalpower. It is another advantage of the door system 10 that this automaticclosure may proceed even if the chain drive 20 or motor 22 is disabled.It is a further advantage of the door system 10 that the system iseasier and less expensive to maintain than an electronically controlleddoor closing system.

In another example, the link 78 may be electronically controlled todisassemble or otherwise release the line 80. In this example, the link78 may be controlled to release the line 80 in response to theactivation of a smoke alarm or security system activation.

In yet another example, the door 12 may be biased to fully or partiallyopen. For example, in response to the drop arm 76 being released, aclosed door 12 may be allowed to fully or partially open. In aparticular example, if the door 12 provides an egress for a facility andthe door 12 is closed, the door release assembly 30 may be automaticallyor manually controlled to release to door 12. In this manner, egressthrough the door 12 may be facilitated.

FIG. 5 is a simplified view of the drop arm 76 and plate 74 in theengaged position. As shown in FIG. 5, the drop arm 76 includes a pivotpoint 90 and a link point 92. The pivot point 90 may be pivotallyconnected to the bracket 32 or other such structural member via a shaft,bolt, rivet, or the like. The link point 92 is secured via the link 78to the bracket 32 or other such structural member of the door system 10.When secured in the engaged position, the drop arm 76 and plate 74 locktogether at an engagement interface 84 to prevent the plate 74 fromturning. In turn, the governor shaft 70 is prevented from turning by theengaged plate 74. That is, the governor shaft 70 is rotationally fixedrelative to the bracket 32 in response to the door release assembly 30being in the engaged position.

As shown in FIGS. 2, 3, and 4, the link 78 may be secured to the linkpoint 92 via a line 80. In another embodiment, the link 78 may beinserted through the link point 92 and into the bracket 32 or other suchstructural member. In this embodiment, by altering an angle of theengagement interface 94, the torque being applied to the plate 74, and alength relationship between the pivot point 90, engagement interface 94,and link point 92, an amount of sheer force exerted upon the link 78 maybe adjusted. By configuring the structural integrity of the link 78 tofall below the sheer force at the predetermined temperature, the droparm 76 may be controlled to disengage at the predetermined temperature.

FIG. 6 is a simplified view of the drop arm 76 and plate 74 in thedisengaged position according to FIG. 5. As shown in FIG. 6, in responseto removal of the link 78 from the link point 92 or the structuralintegrity of the link 78 failing or falling below the sheer forceexerted on the link 78, the drop arm 76 is configured to drop from theengaged position. As the drop arm 76 pivots away from the engagementinterface 94 (shown in FIG. 2) the plate 74 is free to rotate.

As shown in FIG. 2, the free rotation of the plate 74 decouples thedrive sprocket 56 from the drive assembly 28. That is, the rotationalrelationship between the drive sprocket 56 and the hub assembly 64 isdecoupled. As such, the door 12 is free to close or open in accordancewith the bias of the door 12. To control the rate at which the door 12opens or closes, the rotation of the governor shaft 70 is controlled bythe governor 72. In this regard, a hub of the governor 72 is secured tothe governor shaft 70 and a housing of the governor 72 is secured to thebracket 32 or suitable structural member. The hub and housing of thegovernor 72 interact with one another via a viscous fluid or other suchbraking mechanism. The degree to which the governor 72 slows rotation ofthe governor shaft 70 may be determined based upon a variety of factorssuch as, for example, weight or closing bias of the door, fire doorclosing regulations, empirical data, and the like.

FIG. 7 is a detailed view of a horizontally oriented actuator engagingthe drive sprocket 56 according to another embodiment of the invention.As shown in FIG. 7, the door system 10 includes a motor sprocket 96 thatis rotated by the motor 22. In various embodiments, the motor sprocket96 may directly engage the drive sprocket 56 or, as shown in FIG. 5, achain 98 may engage both the motor sprocket 96 and the drive sprocket 56and may be configured to transmit rotation of the motor sprocket 96 tothe drive sprocket 56. In another example, the motor sprocket 96 and thedrive sprocket 56 may be replaced with pulleys and the chain 98 may bereplaced with a belt. These and other such transmission systems arewithin the purview of various embodiments of the invention.

FIG. 8 is a detailed view of a vertically oriented actuator engaging adrive sprocket 56 according to yet another embodiment of the invention.As shown in FIG. 6, the door system 10 includes a worm gear 100 that isrotated by the action of the motor 22. The worm gear 100 is configuredto engage the drive sprocket 56 and urge the drive sprocket 56 to rotatein response to rotation of the worm gear 100. It is an advantage of sucha worm drive that rotation is unidirectionally transmitted.

The many features and advantages of the invention are apparent from thedetailed specification, and thus, it is intended by the appended claimsto cover all such features and advantages of the invention which fallwithin the true spirit and scope of the invention. Further, sincenumerous modifications and variations will readily occur to thoseskilled in the art, it is not desired to limit the invention to theexact construction and operation illustrated and described, andaccordingly, all suitable modifications and equivalents may be resortedto, falling within the scope of the invention.

What is claimed is:
 1. A method of controlling operation of a door, themethod comprising steps of: rotationally fixing a sun gear; rotating amotor to cause a ring gear, which is fixed to a hub assembly, to revolveabout an axis of a governor shaft, thereby rotating the hub assembly;and rotating a door shaft in a first direction in response to rotationof the hub assembly.
 2. The method according to claim 1, furthercomprising the steps of: releasing the sun gear to allow at least oneplanetary gear to freely rotate, an axis of the at least one planetarygear being fixed in place against the rotational resistance of themotor, wherein the hub assembly is operatively connected to the sun gearvia the at least one planetary gear and wherein the hub assembly rotatesin response to rotation of the at least one planetary gear; and rotatinga door shaft in a second direction in response to rotation of the hubassembly.
 3. The method according to claim 2, further comprising thestep of: controlling rotation of the hub assembly via a governor mountedto a governor shaft that is separate from the door shaft.
 4. The methodaccording to claim 1, further comprising the step of: rotationallyfixing the sun gear with a fusible link.
 5. The method according toclaim 1, further comprising the step of: rotationally fixing the sungear with an electronic release configured to release the brake assemblyin response to a signal.
 6. The method according to claim 2, furthercomprising the step of: biasing the door to close.
 7. The methodaccording to claim 2, further comprising the step of: biasing the doorto close via gravity acting on the door.
 8. A device for operating adoor rollable around a door shaft, the device comprising: a driveassembly comprising: a hub assembly affixed to the door shaft, the hubassembly providing rotation axes for a plurality of planetary gears; aring gear affixed to a drive sprocket, the ring gear mating with theplurality of planetary gears; and a sun gear mating with the pluralityof planetary gears, the sun gear having a central axis aligned with ashared central axis of the hub assembly, the ring gear, and the drivesprocket; and a release assembly comprising: a governor affixed to thesun gear, the governor subject to variable rotation resistance; and arelease trigger; wherein the drive assembly and the release assembly areenclosed in a single assembly housing positioned and installed on oneend of the door shaft.
 9. The device of claim 8, wherein the singleassembly housing further encloses a brake assembly operable to engagethe door shaft for limiting rotation of the door.
 10. The device ofclaim 8, wherein the single assembly housing further encloses a hoistassembly operable to engage the door shaft for rotating the door betweenan open position and a closed position.
 11. The device of claim 8,wherein the release trigger comprises a drop arm operable to engage ordisengage with a plate, the drop arm connected with a link holding thedrop arm in an engaged position with the plate.
 12. The device of claim11, wherein the link is fusible to disengage the drop arm from theplate.
 13. A method of controlling operation of a door, the methodcomprising steps of: rotationally fixing a sun gear with a releasetrigger that comprises a drop arm operable to engage or disengage with aplate; rotating a motor to cause a ring gear, which is fixed to a hubassembly, to revolve about an axis of a governor shaft and the sun gear,thereby rotating the hub assembly; and rotating a door shaft in a firstdirection in response to rotation of the hub assembly.
 14. The method ofclaim 13, further comprising holding the drop arm in an engaged positionwith a link.
 15. The method of claim 14, wherein the link is a fusiblelink.
 16. The method of claim 15, further comprising melting the fusiblelink to release the drop arm.
 17. The method of claim 14, wherein thelink is an electronic release device.
 18. The method of claim 17,further comprising releasing the electronic release device upon receiptof a signal.
 19. The method of claim 17, wherein the electronic releasedevice is an electromagnetically coupled link.
 20. The method of claim17, wherein the electronic release device is a solenoid release device.